A study involving 5 chimpanzees was initiated to examine the safety of immunoglobulins (Ig) in regard to hepatitis C. The specific aim of this study is to demonstrate whether safety of Ig is compromised if antibody to hepatitis C (anti-HVC) reactive units are screened from pools from which Ig is manufactured. Two chimps were infused with 25 ml/kg of unprocessed pooled plasma screened for anti-HVC. Three chimps were infused with 1000 mh/kg of Ig manufactured from the same pool. The 2 chimpanzees that received anti-HVC screened, unprocessed pooled plasma became infected with HCV. One chimp became positive for HCV-RNA by PCR one week, and ALT spiked 4 weeks, after infusion. Using RIBA-2, both anti-511 and anti-c100-3 were detected in the serum 7 weeks after inoculation. Anti-c33 appeared 14 weeks, and anti-c22, 22 weeks after inoculation. The other chimp, although receiving the same dose of the same inoculum, demonstrated a different pattern of infection. HCV-RNA was not detected until 9 weeks, and ALT did not spike until 14 weeks, after inoculation. Also, the order of antibody appearance in serum was different. Anti-c22, first antibody to be detected at 10 weeks after inoculation. Then, anti-c33 appeared at 11 weeks and, finally, both anti-c100-3 and anti-511 appeared together, 14 weeks after inoculation. E.M. evaluation of liver biopsies from both animals showed evidence of viral hepatitis. Until now (10 weeks after inoculation), the 3 chimps infused with Ig have not demonstrated evidence of infection with HCV. Thus, whether or not the infused Ig could be infectious still remains inconclusive at the present time. We have, however, conclusively shown that screening units for anti-HVC, that constitute pools from which plasma products are manufactured, will not necessarily lead to non-infectious source material.